Morph Operation
Chooses Shrink, Grow, Opening or Closing.
Opening removes small foreground specks; Closing fills small interior holes.
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Masks & RotoIntermediate
AlphaMatteShrinkandGrow
Morphological alpha cleanup
Shrinks, grows, opens or closes an alpha matte to clean edges, remove tiny holes and repair key or roto masks.
AlphaMatteShrinkandGrow
DaVinci Resolve · Fusion
AlphaMatteShrinkandGrow performs morphological operations on alpha rather than changing the visible RGB image. It is a precise matte-cleanup tool after keying, rotoscoping or any operation that generates transparency.
Overview
What AlphaMatteShrinkandGrow does
AlphaMatteShrinkandGrow performs morphological operations on alpha rather than changing the visible RGB image. It is a precise matte-cleanup tool after keying, rotoscoping or any operation that generates transparency.
Mental model
Think of the alpha as a white silhouette: Shrink moves its border inward, Grow pushes it outward, Opening removes isolated white dirt and Closing fills small black holes.
Common uses
Tighten a green-screen matte
Recover an over-eroded edge
Close pinholes inside a mask
Remove isolated matte noise
Prepare alpha before MatteControl
Inspect alpha-only cleanup
Flow anatomy
Inputs & outputs
The port structure shows how this node fits into a Fusion graph.
Input
Primary image, matte or shape stream processed by the node.
Effect Mask
Optional mask that limits where the node is allowed to act.
AlphaMatteShrinkandGrow
Fusion node
Output
The processed result produced by AlphaMatteShrinkandGrow.
Inspector
Important parameters
Start with these controls before reaching for more complicated workarounds.
Shape
Selects the morphology kernel such as Circle, Square or Diamond.
Radius
Controls how far the alpha boundary is moved or cleaned.
Small values are usually enough for hair and thin details.
Tip: Increase slowly and inspect at 100%.
Output / Process
Chooses whether the node outputs processed RGB, processed alpha, or both.
Output / Preview Alpha
Shows Preview Alpha as a diagnostic preview.
Advanced Options / Manual Iteration Control
Enables Manual Iteration Control.
Practical setup
A reliable workflow
- 1
Connect the keyed or roto image.
- 2
Enable alpha preview.
- 3
Choose the morphology operation that matches the defect.
- 4
Adjust Radius in small increments.
- 5
Return to the full composite and inspect fine edges in motion.
Typical node chain
Key / Roto matte→
AlphaMatteShrinkandGrow→
Clean alpha
Examples
Where this node fits in real work
Tighten a keyed edge
Remove a thin contaminated fringe before final compositing.
MediaInDKeyerAlphaMatteShrinkandGrowMatteControlMerge
Fill small matte holes
Use Closing before a light blur or matte refinement.
MagicMaskAlphaMatteShrinkandGrowMerge
Troubleshooting
Common mistakes
Using a large radius on hair or thin geometry
Judging the result only over the final background
Growing a contaminated RGB edge instead of fixing spill separately
Applying repeated morphology without checking detail loss
Production notes
Practical tips
Use Circle as a safe starting kernel.
Morphology should fix alpha geometry, not color spill.
Compare the matte frame-by-frame around fast motion.
Related nodes